Formation region effects in x-ray transition radiation from 1 to 6 GeV electrons in multilayer targets

Abstract

The formation region effects in x-ray transition radiation have been experimentally investigated. The radiation was generated using 1-6 GeV electrons impinging on two multilayer targets with considerably different periods. The absolute yield of transition radiation was measured and the wide spectral peak in the range from 10 to 30 keV was observed. In the most part of the electron energy range the emission from the short-period radiator was expectedly suppressed, compared to the case of the long-period one. But for the electron energy of 1 GeV an opposite effect, though rather small, of the emission enhancement in the short-period radiator was observed. The conditions, under which this effect is much stronger, are derived and its possible practical value is outlined. The theory accounting for an arbitrary transversal shape of the electron beam and the finite size of the detector is developed. This theory describes rather well the experimental results.

K-shell ionization and characteristic x-ray radiation by high-energy electrons in multifoil targets

“…Such a behavior is typical for the TR intensity in multifoil targets for b ∼ l v [34]. It is a remnant of a much larger maximum in the dependence of TR spectral-angular density on b due to constructive interference of the contributions of separate foils (for a more detailed discussion of the nature of this maximum see [33]). Such a maximum almost (and sometimes completely) vanishes as a result of angle integration of this density (which corresponds to integration with respect to q in our case).…”

“…It considerably depends on the number of foils which the target is split into. Moreover, at b < l v formation region effects take place for the ionization process [31], just like for the TR yield in multifoil radiators [32,33]. In this region the cross section logarithmically grows with the increase of b.…”

“…As a typical example of TR radiator we consider a stack of 50 thin aluminium foils. The radiation spectral density dN TR /dω in this case is defined by the well-known expressions [32,36], which we apply in the form presented in [33] (formula (1)). The thickness of the foils is chosen equal to 10 µm, which corresponds to the highest TR intensity at the maximum of its spectrum situated at ω ≈ 12 keV.…”

Електромагнітні Процеси З «напівголими» Частинками Високих Енергій

“…На тестовому пучку DESY II (м. Гамбург, Німеччина) було проведено експериментальне дослідження впливу напівголого стану електрона на його рентгенівське перехідне випромінювання у багатошарових радіаторах різного періоду [16]. Кожен такий радіатор складався з великої кількості періодично розташованих тонких алюмінієвих пластин, розділених повітряними проміжками.…”